Diaphysis (Long Bones): Terminology of Limb Alteration

10.1055/b-0034-87933

Diaphysis (Long Bones): Terminology of Limb Alteration

Dysmelia is the malformation of a limb due to disturbance in embryonic development and may range from mild hypoplasia of a single bone to aplasia of the entire limb. The radius and fibula are the most commonly affected, followed by the femur, ulna, humerus, and tibia. Abnormalities may be categorized into the following groups of defects:

Fingers (see Table 5.59 )
Hands and feet (acromelia)
Calf and forearm (mesomelia)
Thigh and arm (rhizomelia)
Complex (phocomelia)
Amniotic band syndrome

**Table 5.47 Types of limb shortening**
Diagnosis	Findings	Comments
Acromelia	Hypoplastic hands or feet.	A spectrum of genetic syndromes may have acromelia as one of the skeletal findings. Acromelic dysplasia includes three rare disorders: Weill-Marchesani syndrome, geleo-physic dysplasiaa, and acromicric dysplasia.
Mesomelia	Shortening of the middle limb segments (calf or forearm), often more pronounced in one limb.	Heterogeneous group of bone dysplasias including but not limited to mesomelic dysplasia (many forms/types such as Langer, lethal, upper limbs), chondroectodermal dysplasia, chondrodysplasia punctata, dyschondrosteosis.
Rhizomelia	Shortening of the proximal limb segments (thigh or arm).	Heterogeneous group of bone dysplasias including but not limited to achondroplasia, chondrodysplasia punctata, femoral dysplasia, multiple epiphyseal dysplasia, rhizomelic bone dysplasia (several types).
Phocomelia	Absence or underdevelopment of the proximal portion of the limb with the hand or foot attached to the body by a short flipperlike stump.	Patients have severe but unclassifiable extremity deformities. The deformity may be drug- or toxin-induced (see Table 5.48 ) or genetic. Traditionally, phocomelia has been described as a transverse, intercalary segmental defect; however, genetic and developmental biological research has provided further insight into the complexity of the possible derangements in development, and alternative approaches to classification are under development.